I think anybody with common sense could likely deduce that Marvel is holding back on releasing anything new until SDCC. Marvel has an hour and a half long presentation to discuss Thor: TDW, CA: TWS, GotG, and any other tidbits they want to release. Best opportunity to get the cast in front of a large crowd of fans and reporters and get the movie some attention leading up to its release.

that being the case if any footage is shown will there be an embargo for some time and all the rest of us that cannot attend will get is descriptions. I hope that whatever footage is shown shows how powerful Thor truly is.